1. Field of the Invention
The present invention relates to a liquid crystal display device and a manufacturing method therefor and particularly to a liquid crystal display device having a wide range of viewing angle and a method of manufacturing the same.
2. Description of the Prior Art
In general, liquid crystal display devices have been used as display devices for various electronic equipment, etc. because they can be manufactured to be thin in thickness and light in weight. However, the liquid crystal display device has a disadvantage that the viewing angle thereof is narrower than CRT. Therefore, a technique for widening the viewing angle of the liquid crystal display device has been hitherto proposed.
FIG. 10 is a perspective view showing a conventional liquid crystal display device disclosed in Japanese Patent Laid-open Publication No. 7-199193. In the conventional liquid crystal display device, uneven surface 52 is provided at each pixel 51 on one substrate 56 or both substrates 56, 57. FIG. 10 shows a case where uneven surfaces 52 are provided on the substrate 56. Upon applying a voltage between the substrates 56 and 57, the rise-up direction of liquid crystal molecules 53 between the substrates 56 and 57 is determined by an angle which is dependent on the surface structure of the substrate 56, whereby areas 54 and 55 having different orientation directions are provided at the voltage application time and the visual characteristic is compensated between the respective areas 54 and 55. Therefore, a liquid crystal display device having a wide range of viewing angle can be obtained.
FIGS. 11A to 11D are cross-sectional views showing a series of steps of a method of manufacturing a substrate used for the above conventional liquid crystal display device.
First, thermoplastic resist 61 is coated on substrate 60 with electrodes (FIG. 11A).
Subsequently, the resist 61 is partially shielded and then exposed to light to dissolve and remove undesired portions of the resist, whereby resist 61a remains in a partial area (FIG. 11B).
Subsequently, the substrate 60 is heated to deform the resist 61a, thereby forming resist 61b having an uneven structure surface respectively (FIG. 11C).
However, the conventional liquid crystal display device described above has a disadvantage that it has lower transparency as compared with similar organic materials having no photosensitive group because a photosensitive resist is used even when the whole-surface light exposure is performed, so that a display image is darkened or colored.
Furthermore, it is described in the above publication that according to the method of manufacturing the substrate used in the above convention al liquid crystal display device, slant and uneven portions are formed in a wide range by deforming the thermoplastic resist. However, the thermoplastic resist is actually deformed at only the end portions of the residual resist like the resist 61c, and it is difficult to form the slant and uneven portions in a wide range (FIG. 11D). Accordingly, the conventional liquid crystal display device has a disadvantage that a regulation force is insufficient to keep the uniform rise-up direction and thus a stable orientation state cannot be obtained.
An object of the present invention is to provide a liquid crystal display device having a wide range of viewing angle characteristic with which transparency is enhanced and a stable orientation state can be obtained, and a method of manufacturing the liquid crystal display device.
In order to attain the above object, according to a first aspect of the present invention, a liquid crystal display device having a pair of substrates and a liquid crystal layer disposed therebetween, is characterized in that orientation control slope portions composed of an organic film are provided on at least one of the substrates so as to be slopewise formed in different directions within each pixel, and an opaque shielding electrode is disposed at a boundary portion at which the slope direction is varied in each of the orientation control slope portions.
According to a second aspect of the present invention, a liquid crystal display device having a fir s t substrate, a second substrate and a liquid crystal layer disposed between the first substrate and the second substrate, is characterized in that the first substrate comprises a first transparent substrate, first transparent electrodes provided on the first transparent substrate, orientation control slope portions which are slopewise formed in different directions within each pixel and composed of organic film and provided on the first transparent electrodes and a first orientation layer coated on the orientation control slope portions, the second substrate comprises a second transparent substrate, one or more second transparent electrodes provided on the second transparent substrate and a second orientation layer coated on the one or more second transparent electrodes, and an opaque shielding electrode is disposed a boundary portion at which the slope direction is varied in each of the orientation control slope portions.
According to a third aspect of the present invention, a liquid crystal display device having a first substrate, a second substrate and a liquid crystal layer disposed between the first substrate and the second substrate, is characterized in that the first substrate comprises a first transparent substrate, pixel electrodes provided on the first transparent substrate, first orientation control slope portions which are slopewise formed in different directions within each pixel and composed of organic film and provided on the pixel electrodes, and a first orientation layer coated on the first orientation control slope portions, the second substrate comprises a second transparent substrate, one or more opposite electrodes provided on the second transparent substrate, a second orientation control slope portions which are slopewise formed in different directions within each pixel and composed of organic film and provided on the one or more opposite electrodes, and a second orientation layer coated on the second orientation control slope portions, the first and second orientation control slope portions being formed so that the confronting surfaces thereof are substantially parallel to each other, and an opaque shielding electrode is disposed at a boundary portion at which the slope direction is varied in each of the first orientation control slope portions.
According to a fourth aspect of the present invention, a liquid crystal display device having a first substrate, a second substrate and a liquid crystal layer disposed between the first substrate and the second substrate, is characterized in that the first substrate comprises a first transparent substrate, pixel electrodes provided on the first transparent substrate, first orientation control slope portions which are slopewise formed in different directions within each pixel and composed of organic film and provided on the pixel electrodes, and a first orientation layer coated on the first orientation control slope portions, the second substrate comprises a second transparent substrate, one or more opposite electrodes provided on the second transparent substrate, a second orientation control slope portions which are slopewise formed in different directions within each pixel and composed of organic film and provided on the one or more opposite electrodes, and a second orientation layer coated on the second orientation control slope portions, the first and second orientation control slope portions being formed so that the confronting surfaces thereof are substantially parallel to each other, and an opaque shielding electrode is disposed at a boundary portion at which the slope direction is varied in each of the second orientation control slope portions.
According to a fifth aspect of the present invention, a liquid crystal display device having a pair of substrates and a liquid crystal layer disposed therebetween, is characterized in that orientation control slope portions composed of an organic film are provided on at least one of the substrates so as to be slopewise formed in different directions within each pixel, the organic film being composed of organic material containing no photosensitive group.
According to a sixth aspect of the present invention, a liquid crystal display device having a first substrate, a second substrate and a liquid crystal layer disposed between the first substrate and the second substrate, is characterized in that the first substrate comprises a first transparent substrate, first transparent electrodes provided on the first transparent substrate, orientation control slope portions which are slopewise formed in different directions within each pixel and composed of organic film and provided on the first transparent electrodes and a first orientation layer coated on the orientation control slope portions, the second substrate comprises a second transparent substrate, one or more second transparent electrodes provided on the second transparent substrate and a second orientation layer coated on the one or more second transparent electrodes, the organic film being composed of organic material containing no photosensitive group.
According to a seventh aspect of the present invention, a liquid crystal display device having a first substrate, a second substrate and a liquid crystal layer disposed between the first substrate and the second substrate, is characterized in that the first substrate comprises a first transparent substrate, pixel electrodes provided on the first transparent substrate, first orientation control slope portions which are slopewise formed in different directions within each pixel and composed of organic film and provided on the pixel electrodes, and a first orientation layer coated on the first orientation control slope portions, the second substrate comprises a second transparent substrate, one or more opposite electrodes provided on the second transparent substrate, a second orientation control slope portions which are slopewise formed in different directions within each pixel and composed of organic film and provided on the one or more opposite electrodes, and a second orientation layer coated on the second orientation control slope portions, the first and second orientation control slope portions being formed so that the confronting surfaces thereof are substantially parallel to each other, the organic film being composed of organic material containing no photosensitive group.
The organic film constituting the orientation control slope portions is preferably composed of material selected from the group consisting of acrylic resin, polyimide, polysilazane, low-temperature curing type polysilazane and benzocyclobutene.
According to a eighth aspect of the present invention, a method of manufacturing a liquid crystal display device comprising the steps of:
(1) coating an organic material on one or more electrodes of at least one of a pair of substrates to form an organic film;
(2) coating photoresist on the organic film;
(3) exposing the photoresist to light;
(4) immersing the substrate in developing solution to perform development and subjecting the organic film to wet etching with the developing solution;
(5) exfoliating the photoresist;
(6) deforming the organic film by heating the organic film, and providing on the substrate orientation control slope portions which are sloping in different directions respectively and formed of organic film; and
(7) coating an orientation film on the orientation control slope portion.
The developing solution is preferably an alkali developing solution, and the organic film is preferably composed of material that is dissolved in the alkali developing solution.
According to a ninth aspect of the present invention, a method of manufacturing a liquid crystal display device comprising the steps of:
(1) coating an organic material on one or more electrodes of at least one of a pair of substrates to form an organic film;
(2) coating photoresist on the organic film;
(3) exposing the photoresist to light;
(4) immersing the substrate in developing solution to perform development;
(5) wet-etching the organic film;
(6) exfoliating the photoresist;
(7) deforming the organic film by heating the organic film, and providing on the substrate orientation control slope portions which are sloping in different directions respectively and formed of organic film; and
(8) coating an orientation film on the orientation control slope portions;
The developing solution is an alkali developing solution, and the organic film is composed of material which is not dissolved in the alkali developing solution.
According to the liquid crystal display device of the present invention, the orientation control slope portions are formed so as to be slopewise in the different directions within each pixel, and thus the orientation stability of domains is enhanced. Further, since the orientation control slope portion in each pixel is formed of the organic film, transparency is very excellent.
According to the manufacturing method of the present invention, since the organic film which can be formed at a large thickness is subjected to wet etching and then heated to form the orientation control slope portions on the substrate, the orientation control slope portion which is gently and widely sloping in different directions within each pixel can be surely obtained.